The 1935 film “The 39 Steps” is a very, very serious thriller in which a bored fellow goes out for the evening, comes home with the wrong woman and finds himself amid a vast conspiracy that eventually has him running for his life.

The 2005 stage version keeps the story (first told in a 1915 novel) and a fair amount of the film's dialogue. But the tone is another matter.

Case in point: In the Sheldon Vexler Theatre's delightful staging, any time that the title is referenced it's followed by a hyper-dramatic “dun-dun-DUN” musical cue.

Kai cast her leads well, too: All four are adept at physical comedy, and this show has plenty of it. (The sequence in which the hero, played by Simpson, is pursued across the top of a moving train is particularly well-done.)

The show also pays homage to Alfred Hitchcock, who directed the film. There aren't quite as many visual keys to his work as there were in the touring show that played at the Majestic Theatre a few years ago — this show has a pretty spare look — but there are enough references scattered about. There's some music from “Psycho,” a “North by Northwest”-style man vs. plane chase, and there is a video introduction from Hitch himself (the terrific Rick Lukens). The video (shot by Travis Nobles) has the grainy quality of an old movie, a nice touch.

Ken Frazier's set is simple and inventive. Dozens of trunks are piled up, and they're pulled out as needed, becoming train cars, a dinner table, a bed or a fireplace. (The fireplace bit is particularly fun: Leibowitz, in a memorable turn as a female innkeeper, opens a small trunk and makes reference to the roaring fire. When nothing happens, he looks pointedly up at the tech booth, and repeats the line louder. The fireplace gets a rosy glow, accompanied by the crackling sound of logs burning.)

There were a few spots opening night in which musical underscoring overwhelmed the dialogue, a problem that is easy to address.

The show is, as Kai says in her director's note, “a rollicking bit of nonsense,” and well worth catching.